I mean you watch the guy in junior and he has everything. Size, speed, hands, shot, vision, passing. He's the total package. Hell, he even wins nearly every board battle by out-thinking his opponent. I doubt he will dominate along the boards in the NHL like he does now, but aside from that it looks like he will be top tier right from the start.
He's faster than most people in the NHL. He has better hands than most people in the NHL. He thinks the game at a higher level than ANYBODY in the NHL. The plays he makes in the OHL will translate over perfectly. Watch the way he protects the puck and seems to know where his teammates are at all times. Watch his highlights from the WJC where he makes ludicrous passes to Petan. Those are passes you'd only see a handful of NHLers able to make.
Crosby dominates because of his strength going into corners, his speed, his shot. In the CHL, Crosby was already a man strength-wise it seemed. He was so powerful in the way he skates and the way he could do his infamous 10-2 shielding of the puck. Only someone like Jeff Skinner is able to do that too.
McDavid is still weak in comparison and I feel that could be the only drawback going into next season. If he had the raw strength to muscle his way past people or wire shots at the velocity Crosby could at the same age, we would be calling him a significantly better prospect.
If McDavid can get that strong as learns how to shoot as hard as Crosby, he will easily be a better player.
I'd like to stress that strength in the CHL is everything. It's why you see older guys who will go nowhere usually high up on the scoring lists (most of the time). One year they are a 18 year old 4th line who has relatively no skill, and the next they are an overager who has 40 lbs of muscle over most opponents. They manhandle them and grind out goals relatively easy, and then fade into obscurity.